The present invention relates to a turbofan-type turbojet engine having an afterburner, more particularly a flow mixer and afterburner flame stabilizer for such an engine.
In known turbofan-type turbojet engines, a duct within the outer casing of the engine divides the airflow downstream of the low pressure compressor into a cold flow portion and hot flow portion. The air passing into the hot flow portion is directed into the combustion chambers, mixed with fuel and ignited. The cold flow air passes around the combustion chambers without being mixed with fuel or ignited.
In such engines, controlling the bypass ratio (the ratio of air flow through the cold flow duct with respect to that flowing through the hot flow duct) optimizes engine operation over a wide range of conditions, from subsonic cruising (with a high bypass ratio) to high altitude, high speed operation (with a low bypass ratio).
It is also known to equip such turbofan engines with afterburners to enable higher altitude, higher speed operations. As is well known in the art, additional fuel is injected into the hot gas flow, downstream of the combustion chambers, and ignited to augment the thrust of the engine.
It is known to vary the bypass ratio by directing at least a portion of the cold flow into the hot flow gas stream downstream of the afterburner combustion area, as typified by U.S. Pat. No. 3,118,276 to Keenan et al.
Known afterburner systems typically incorporate an afterburner flame stabilizer and it is also known to tap a portion of the cold flow to cool the afterburner stabilizer as noted in U.S. Pat. No. 3,595,024 to Kohler.
The known systems, however, cause a loss of pressure in the bypass flow causing the flow to deviate from its optimum flow path and incurring pressure losses.